Nimrod is a mutant-hunting Sentinel from an alternate future who was created by the Sentinels who ruled that timeline. When Rachel Summers traveled back in time to the present, he followed her. In the process — due to an altered timeline following Kulan Gath's occupation of New York — he saved the life of construction worker Jaime Rodriguez, who in gratitude offered him a job and a home with his family, not realizing who or what the Sentinel truly was.